Photographic film



Feb. 23, 1932. w, G s ua 1,846,230

PHOTOGRAPHIC FILM Filed Dec; 11, 1,930

High/Speed Emulsion ll/I'lliuun 6812112611.

Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE WILLIAM G. STUBER, OF ROCHESTER, NEW YORK, ASSIGNOR T0 EASTMAN KODAK COM- IPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK IPHOTOGRAPHIG FILM Application filed December 11. 1930. Serial No. 501,526.

This invention relates to a photographic film having new characteristics.

An object of the invention is to provide a film of such character that developed negatives made with it may be more easily judged as to detail and general quality. A further object is to lessen halation in the film.

The single figure of the drawing shows in enlarged cross section an embodiment of my invention.

Films have been made on opalescent support or with opales cent backings, and various patents have shown an opalescent emulsion layer obtained by adding a suitable material to the entire emulsion. For this purpose, for example, rubber latex and starch have been suggested.

I use an opalescent layer of such type in the production of a film of a new kind. I employ a translucent, sensitive, light-diffusing layer, which will retain this property, as an undercoating, placing the principal sensitive layer over this as a distinctly separate coating or layer. This may be carried out in several ways.

The drawing may be used to illustrate any of these. A transparent support 1 of any of the customary compositions, such as cellulosic derivatives, has coated on the back a layer 2, which may be of plain gelatin to prevent curling, or it may be of any type employed to prevent halation. On the opposite side is coated a layer 3 which contains a white, light-diflusing material such as starch.

This material is present in a sufiicient quan- 'tity to render the layer of a white appearance, and distinctly light-difi'using, but not opaque. Over this and firmly adherent to it is another layer 4 which consists of a so-called fast emulsion. This layer is coated over the layer 3 preferably after the latter has dried. The emulsion of the layer 4.- may be of the ordinary type, or it may be sensitized with dyes to make it color sensitive.

' The layer 3 is a colloid layer of low hotographic sensitivity and contains the lig t diffusing material. I do not limit myself as to the ingredients of this layer 3, as I may wish to include any colloid or carrier, any translucent or white light-difiusing substance, and

any other substance for any purpose whatsoever.

A preferred embodiment of my invention is a transparent support of a cellulosic derivative coated on the back with a gelatin layer to prevent curling, on the reverse side a slow silver halide emulsion layer containing starch, and over this a fast silver halide emulsion rendered orthochromatic or panchromatic. As stated, however, in place of the ordinary non-curling layer, I may use a special coating with or without gelatin to prevent halation.

With such a film it is possible for the user, especially a commercial photo finisher, more rapidly and more accurately to judge the quality and printing time of negatives made with it than with ordinary clear film. This is particularly true with thin or under exposed negative. In such negatives, especially, fine detail may more easily be seen. The light diffusing material does not to any extent effect the exposure time required in printing, nor eflect the quality of the print in any detrimental way. In fact it is possi: ble, by providing a relatively thick layer 1n the coating 3 to secure a little softening or diffusing quality in the print. This, however, is not noticeable with ordinary thicknesses.

The particular construction used in my invention has advantages also over the method of coating the light diffusing layer on the back opposite the emulsion side. If such a layer containing a light diffusing material is coated on the back, it becomes difficult in the ordinary dark room light to tell which is the emulsion side, an important detail in printing. Both sides feel the same to the touch and appear similar to the eye. Film made according to this invention is glossy and smooth on the back, enabling the operator to determine immediately which is the emulsion side just as easily as with ordinary film.

It also avoids the necessity of preparing the support especially for matte films. The fact that the difi'usive material is in the lower portion of the emulsion, which is slow, results in the greater part of the ima e being in the outer layer Where it is sharp, w ich would not be the case if the diffusing material extended throughout the emulsion layers.

I consider as included in my invention all variations and equivalents coming Within the 5 scope of the appended claims.

What I claim is: Y

1. A photographic film comprising a transparent support, a 810W sensitive silver halide layer thereon containing a perma nently translucent light-diffusing material, and over this a fast silver halide layer.

2. A photographic film comprising a transparent support, and two silver halide layers carried thereby, one coated over the other, the under of said layers being a slow emulsion containing a White 1i ht-diflusing material which is not effected y the ordinary developing and fixing baths, and the upper of said layers consisting of a fast emulsion. w

3. A photographic film comprising a transparent support of a cellulosic derivative having on one surface a layer containing gelatin and a light absorbing dye and tending to prevent curl and halation and on the reverse surface a highly sensitive silver halide layer, and between said support and said sensitive layer another layer which has low photographic sensitivity and contains a White light-diffusing material which is not effected by the ordinary photographic developing and fixing baths.

4. A photographic film comprising a 95 transparent support of a cellulosic derivative, on the back a layer containing gelatin, on the reverse side a fast sensitive silver halide layer, and between said support and said sensitive layer a slow silver halide emulsion layer con- 40 taining a White light-diffusing material which is not effected by the ordinary developing and fixing baths.

Signed at Rochester, New York, this 8th day of December, 1930.

- WILLIAM G. STUBER. 

